1. triangular areas of land formed by deposits of sediment at the mouth of a river
Usage: geography
2. the fourth letters of the Greek alphabet (Δ, δ)
3. symbols representing change or difference in mathematics and science
Usage: mathematics; science

Examples

• The Nile and Mississippi rivers have formed large deltas over thousands of years.
• Many deltas are fertile areas perfect for agriculture.
• The students learned to write the Greek deltas in their alphabet lesson.
• In physics class, we used deltas to represent changes in velocity.
• The equation showed deltas indicating the difference between two values.
• Coastal deltas are important ecosystems for many species of birds.
• The ancient Greeks used deltas as both letters and mathematical symbols.